Radio relay distributing system



I-IUIIIIIIII Oct. 7, 193 0. CLEMENT 1,777,690

RADIO RELAY DISTRIBUTING SYSTEM Original Filed Oct. 28, 1924 6 Sheets-sheaf 1 IC I76 C0467 TIM mavr mv r/ms K4104; cl?

Oct. 7, 1930. E. E. CLEMENT RADIO RELAY DISTRIBUTING SYS'ITBI Origihal Filed Oqt. 28, 1924' 6 Sheets-Sheet 2 6 Sheets-Sheet 3 Oct. 7, 1930. E. E. CLEMENT RADIO RELAY DISTRIBUTING SYSTEM Original File d Oct. 28, 192

gwuentoo E. E. CLEME'NT 1,777Q690 RADIO RELAY DISTRIBUTING SYSTEM Oct. 7, 1930.

Original Filed Oct. 28, 1924 6 Sheets-Sheet 4 Oct. 7, 1930. E. E. CLEMENT RADIO RELAY DISTRIBUTING SYSTEM Original Filed Oct. 28, 1924 6 Sheets-Sheet 5 z W H g .Qw E 1 7 w QN M 7 3 IE NHN Och-7, 1930. E. E. CLEMENT RADIO RELAY DISTRIBUTING SYSTEM Ofiginal Filed Oct. 28, 1924 6 Sheets-Sheet 6 gram of a portion of Fig. 1 showing subtion for supervision and control by expert ably associated with the parts at the different sitioned'to form part of a typical distribut- Patentecl Oct. 7, 19 30 UNITED STATES PATENT OFFICE EDwARnn dLEMENT, or wAsHINorboN, n s'rnro'r or ooLUMnIA, AssIeNon WARD r. COLLADAY, or wAsHINero prsrnrcrr or cont nu n x RADIO zELAY msrnmu'rI e SYSTEM 1 Original application filed October 28, 1924, Serial No. 746,358. Patent No. 1,672,872, dated June 5, i928.

a Divided and this application 'filed August 1, 192 5. Serial No. 47,546. v The present application is a division of my 2 Fig.3 is a diagram showing the subscriberis i double detector receiving set divided into two single demodulating units, one located at the subscribers station and the other located at the central oflice, the first detector bein at 55 the subscribers station and sending I ong waves through the subscribers line to the second detector at central, which sends back audioflwaves to the subscribers telephone.

copending appllcation, Serial No. 746,358, filed October 28,1924, Patent N 0. 1,672,372, June 5, '1928. The invention relates to systems of radio broadcast distribution, has for its object the provision of such a system in which the broadcasted matter may be relayed through one or several relay stations without loss in quality and to selected sub- V scribers receiving stations under local cen- Fig. 4 is a diagram showing a modifica e tralized supervision and control of the retion of the circuit of Fig. 3, in which regenception, or of both relaytransmission and eration is adde at the subscribers station, reception. and the intermediate wave line couplin'glat I A further object of the invention is to central is included in the cord circuitQf, a provide a system of broadcast distribution Fig. at is a diagram ofa further niodifica- 5 in which the necessary receiving apparatus tion showingthe said cord circuit provided is simplified both in structure and operation with the same elements as in Fig. 4 except by the provision of receiving devices having the battery which is in two units, one for complementary parts at the receiving statalking and telephone signalingfand the tions and at a centralized station common to otherfor the detector tube plate circuit. i 1 a group of receiving stations thereby re 7 Fig. 5 is a schematic 'diagram'showing the ducing the amount of apparatus necessary -relat1on'of units of any type connected up at the receiving station and placing an imto perform the functionsof the circuits portant portion thereof at the central sta- A shown in Figs. 3, 4 and 4. v; I

Fig. 6 is a circuit diagram of double modu- 76 operators; i lating apparatus. i I .j t A further object of the invention is to ig. 7 is a circuit diagram of relay appaprbvide a system ofTradio distribution and ratus for stations 1 301 e, a reception in which the receiving apparatus Fig. 8is a circuit d agram showing means is situated partly at receiving stations and primarily intended forA andB stations, but partly at a central station common to a group which may be located also at C stations, for of receiving stations, the parts at thecenpicking up any single modulated .carrier tral stationbeing arranged to be interchangewave which it is desired to put out in the system, and changing this into a double mod ulated wave. by heterodyning, amplifying, s5 and transmitting the'modulated intermediate frequency carrier or beat, on a short carrier 7 wave whose frequency is the mean of the frereceiving stations. a r i a 7 Various other objects'of my invention will be apparent from a perusal of the following specification and the'drawings accompanying the same. 5

My invention is illustrated in the accome i pr panying drawings, in which:

Fig. 9 is a circuit diagram similar to Fig; I Fig. 1 is a geographical diagram ofthe SshoWing a modified form of apparatus that area of the United States divided with' remay 'be used in Fig-.8, employing theautt jspect to standard time, showing stations p'o dyne principle for receiving instead I of a quencies of the originalcarrier and the heterg odyning oscillator waves. a

double tube heterodyne circuit. 1 v

Fig. lOis a' circuit diagram showing equip} ment' supposed to be located at theA, B, and C stations, for receiving on any single'inodulated'carrier wave, heterodyning and detecting the same and modulating the beat taken 2! System embodyingthis'invention; Fig. 2 is an enlarged geographical "di division of distribution in localized or districted areas. 3" a I? therefrom on to the standard frequency short carrier wave of the next succeeding orderof stations. If located atstation A, the beat would be modulated and transmitted on the B frequency, and if located at a station B, transmission would then be on standard carrier wave C. f' Referring to the drawings, and particular- 1 to Fi 1, this is a diagram of the United tates ogAmerica, divided by lines t, t and t into four divisions marked respectively Eastern standard time, Centraltime, Mountain time,'.and Pacific coast time. It happens that .the town of Hutchinson, Kansas, is within fifty miles of the geographical centerof the United States and hence have shown this town with three rings around it, and the letter A, indicating the location either of the headquarters or master station of the entire system. In each division'there is onestation with'two rings around it, and

. marked B. These are the head or master Other stations are shown in each division their respective divisions.

I It is to be noted that Washington, D. C., is the of the Eastern standard time division, which district stations of the-several divisions,

which under certain conditions serve as relay stations between the A stations and the other B stations for their respective divisions.

with one ring each, and marked B. These are district stations, and receive either directly from the A stations or on occasion by relaying from the head or master B stations in This illustrates the general manner 'of distribution, and will be referred tohereinafter. r

Fig. 2 shows on an enlarged scale a portion may be regarded as one or more districts, as it contains a number of district stat ions B. The main function of this figure is to show the relation between the district station andthe local or -regional distributing centers C.

' head or master B station in the eastern division, while other 'townsfromBoston! to Augusts. are shownin Fig. 2 with one ring as ordinary distributing centers each serving a number (which in practice would be very considerable) of outlying localor regional exchange centers marked C. Around each of these local stations or centers C are grouped. subscribers. v y

In Fig. 1, I have shown eight district stations B in the eastern division, ten in the central division, and six each in the Mountain and Pacific coast divisions, o'r a total of (thirty. This of course is illustrative only and not to be taken as final either in position- I ing or numerical selection. As a matter of fact if .the area of the United States he dividedup into substantially equal districts, zippro'ximately one hundred district stations would be a convenient. number, but it is doubtful whether the trafiic would require this many district stations at first. In Fig.

detector tube 85. a The inputcircuit ma 2, I have shown a larger numberof stations in part of the same territory, or .B stations,

.three orders of stations, B, C, and D, is allotted a single carrier. wave frequency for receiving, l'llCh is common to all the stations of the same order, and that say ten interme- 1 diate or long wave frequencies may be modulated' thereon, each intermediate frequency being in turn modulated at audio frequencies intended for distribution. At certain-times these ten intermediate frequencies may all be used at the master-station A and broadcasted on the B carrier wave to all the B stations, which in turn'will democlulate the initial cara a a rler, amplify and reimpose the sanic intermediate frequencies and modulations on the common 0 carrier wave and so relay them to all the C stations, which in turn will demodulate the carrier waves received by them and re-' impose the same upon the common carrier wave allotted to all the D or subscribers staquencies in useby station A and at such times diate frequencies are simply passed along by relaying until they reach the subscribers, who receive'them'in the original package, so tospeak, so that it .is entirely possible to say.

truthfully to the subscribers that they receive and actually hear the original audio mod-elm tions, with equal 'efliciency from all points,

tions. At other times there may be only one or two or even none of the intermediate fre-' foreign or domestic; and this in spite of the simplicity of their instruments. v

Fi 2 shows geographically the method of dlSt1lblltl0Il in the district or B areas and the relation in general between B and C stations.

Referring to Fi v 3, the s'ubscribers station A is equipped with a' radiophonc receiving device including an antenna circuit 28, tuned as usual, and coupled by means of coils 29 to the input side or grid circuit 126 of the be tuned by means of condenser 129, but it 1s to be understood that-"this condenser and also the tuning elements in theantenna circuit may be ad usted once for all if the subscribers all work on a constant frequency, as hereinbe fore 'set forth. The plate circuit 127128 of the tube 85 includes one winding 123 of a tuned filter coupler, the other side of which 121 is connected to extensionsl8 and 19 of t responding twin plugs P the subscribers telephone line circuit 18-19. The coil 123 is shunted by a condenser 124, and the'ca'pacity and inductance are so adjusted that the short circuit thus formed is 5 resonant to the intermediate frequency waves imposed on the short carrier waves reaching the subscribers instrument through the antenna 28. The variable condenser 122 is included in series with the coil 121, because of i the line connection, tuning of the line being accomplished at both ends as will presently appear. w

t the central oflice, the line Wires 18-19 are connected to any desired number of answering and multiple jacks typified by the single ack J, and is provided with extensions 18 -19 passing to the radio department or radio switchbo'ardR in the'upper part of the figure. The telephone jacks are 20 intended to be interconnected with other jacks for telephonic purposes through a standard cord circuit 20-21, 22-23, having terminal plugs P-P, and bridged by a common talking and signaling battery B, feeding through 25 the two halves of repeating coil I and also feeding through a ring on each plug and test "thimble on each jackto the cut off relay circuit 19, so that whenever a plug is in a jack of the line 18-19, circuit from battery to the cut off relay L willbe completed and the line relay L' with its connection to the main battery B will be cut off and removed entirely from the line. In this 'cut off portion of the cord circuit are "inserted supervisory lamp signals, s-s', adapted to be shunted by contacts controlled by supervisory relays included in the conductors 22-23, respectively. 'These relays respond to current in the su scriberslineswhen they are interconnected,

' 4 and the lamps lig htwhen'the subscribers hang up their receivers. T On the radio switchboard R, the same line is provided with jacks typified by jacks "J 7-J F. As shown, these are in pairs, for

4 convenience only, and toavoid-puttin'g a large {number of contacts in one ack. The upper 'jack J isa duplicate of the telephone jack 'J, and has its contacts connected in parallel to the samefconductors, respectively. Jack to J is a radio jack pure and simple, and is connected-to the same line wires 18**19 through a tuned filter coupler composed of "coils 115 and 117 and condensers 116 and'11 8. The elements 115 and 116 are employed in E5 conjunction with the elements 121-122 at the subscribers station to tune the line circuit t'o'resonance at thefrequency of the long f wave's sent forward as demodulated by the "fsubs(':riber, The elements 116-117 at central cofare included inthis 'figure between the line i '1: and the jack'because by this means the tuning of the line can be made constant and ad any special form of receiver desired.

' 'justed once for all. The cord circuit adapted fto cooperate with these twin jacks'has corpreferably t, ife

containing a by-pass condenser v100;

connected mechanically so they can be inserted and removed from the jacks atlthe same time. The plug P is the terminal of a standard talking circuit -91, with battery B bridged across it through coils92-93, and 70 provided with supervisory lamp 101, the controlling shunt therefor 102, the supervisory relay 103 and the talking shunt therefor 104, also with special test coil 106 supplied-with a radio tone test through wire 108 from the i commutator 107. \Vhen this plug is inserted in the jack J thecut ofi' relay L of the telephone line is pulled up and the line cleared of all telephone switchboard connection, for radiouse. 1 *i I The plug P forms the terminal of a radio detector circuit, the tip and sleeve of the plug being connected through conductors" 96-97 with the grid and the filament respectively .of the detector tube 86. The plate circuit 97-98 1:

of this tube is connected to the outside terminals of coils 94-95 which with the bridged coil 92-93 form the usual repeating coil eonnection between two ends of the standard bridged battery cord circuit. The batteryBcgo bridged between the windings 94-95, has its positive terminal connected to the plate through coil 94 and wire 98, and the conductors 97-98 are bridged by a conducto'r199 95 The result of this arrangement-is as follows: The subscriber calls for radio service by moving his switchhook at station A, up and down rapidly. This flashes the line lamp before the telephone operator, who transfersfii the line over an order trunk to the radio operator, who thereupon inserts the twin plugs 1 -1 into the jacks J ".-J This pulls up the cut off relay L clears the'lin'e that the subscriber has closed his filament circuit at the substation, radio waves received on his antenna 28 are demodulated, and their long wave or intermediate 'frequencycom- :1 ponent, carrying the audio modulations, is

transmitted to line through the filter coupler 121-123. From line it passes through the filter coupler -117 and through the wires 96-97 :to the grid circuit of thetube 86. Thetn varying potentials thus produced the grid circuit of the tube are reproduced in current changes in the circuit 97-95-13-94-98. The superaudio frequency waves are absorbed by the circuit 99 and the condenser 100, andc-i o pure audio frequency waves are propagated through the repeating coil 94-95-92- 98, into'the telephone line circuit, througl1 'tl1e plug P, the jack J 7, multiple'wires 18 -19 and line circuit 18-19, At the subscribers -qga station these audio wavesmay be received on his ordinary telephone receiver a,or 'upon Referring now to Fig; 4, I have shown therein a modification of-the circuit of Fig. 3,'

in which the 'following features are introduced: First, I provide a feed back coil or tickler 130st the subscribers station; a special receiving telephone 133 with a terminal plug 132 adapted to be inserted in the jack 131 brid ed across the telephone line outside of the lter coupler 121-423; and la" tly I have removedthe central oflice filter coupler 115 117 from its position between the line and the'jack J as in Fig. ,3 and instead thereof have located this coupler in abridge of the cord circuit',96- 97, thus doing away with the twin vplu P and its connections.

.This also reduces t e number of couplers required, and most important of all enables the complete radio-cord circuit to be used with telephone jack, since the terany ordinar is an ordinary telephone terminal plug minal plug. F orithe reason stated, Ihave designated both jacks in this figure by the let ter J, the lower one being at the telephone through conductors 96-,97 across'the switchboard and the upper one at the radio switchboard. Both may be used interchangeably, or an ordinar telephone switchboard may be used for re. io'purposes without any chan e other than adding the filter coupler, the etector tube and other connections to an ordinary stand it possible to give radio service on any telephone switchboard, using the same operators if desired, for both services, It also makes it ossible to' lengthen the life, of a telephone sw1tchb6ard,'by rewiring the cords and conveptin it into a radio switchboard.

, n coupler 29 are the same as before; the grid circuit is L25126, the plate circuit 127128 includes a tickler coil 130, and the other arts have been referred to, At the centre station the plug P is connected as in Fig. 3 to the repeating coil, battery, supervisory lamp, controllingrelay therefor, tone test,

etc. The coil 115 of the central ofiice filter of the plate circuit-at will by means of a- .switch 98. This coil 134 feeds back into the grid circuitwaves at intermediate frequency,

as received over the line, and is intended to.

given higher ratio of amplification in the audio current returned to the subscriber than would be possible without'it. .It should be noted however, that instead of thususing the regenerative principle, I contemplate employing radio and audio amplification'in one or more stages of each, inserted between the ard answering plug cord." This interchangeability of the parts, make ig. 4, the antenna circuit 28 and thedetector tube 86 and the plug P or P. (Fig. 4.

In Fig. 4 I have shown a modification of the cord circuit in Fig. 4 which consists in providing a separate battery B for the plate circuit 97-98 of {the tube. This battery is located neXt to the plate, and the by-pass condenser 100 is bridged across the terminals of the repeating coils 9 495. This approaches more nearly to the common or standard meth- -od of connecting circuits than the bridge circuit of Figs. 3-4, and while probably not more efficient, is a little more flexible, as it permits the voltage of the B batterylo be varied at will, without reference to the.voltage of the battery B which according to telephone practice is constant at abollt 22 volts. Thus, if am lifier tubes are used between the tube 86 an the coils 94- -95, a separate plate battery would be required for the amplifiers, giving -a higher voltage accordingtocommonpractice, The operation of Figs. 4-4 is as follows: The subscriber may call as before and in response to his call theradio operator gives him a cord circuit with terminal plu P whereupon his unit through the detector tube demodulates the'short wave carrier received on antenna circuit 28, and sends the intermediate or long wave modulation thereof through theline wires to central, where it passes to the jack J and the plug P and is repeated by the tuned filter coupler 115"117" into the grid circuit .9697 of the tube 86. Through this tube, and any amplifying tubes.

; which may be employed, the audio modulations are first detected and then amplified and 'sent back through the repeating coil to the plug P and the jack J to the subscribers line. At the subscribers station they are received either on his regular telephone receiv-' er, or on the special telephone 133 which typifies any kind of receiver which it may be found exped ent and desirable to employ.

I contemplate dividing the cord circuits shown in Figs. 3, 4, 4", in classes, the first class being like those shown herein, without an amplification; the second class having su ficient audio amplification or radio amplificasubscribers table talker; and those of higher tion, or both,to insure'good operation of the.

classes having more amplification, serving for the operation of loud s cakers giving varying volumes of sound. hus'it may be stated that a- No. 1 cord circuit would be as shown, with'only one detector tube and the subscribe'r would therefore receive his audio'message on a head telephone or on his ordinary telephone receiver held to his ear; with a No:

2 set at central there would be'one stage of audio amplification sufiicient at the subscribers station for a tabletalker which would not annoy the neighbors; a No. 3 set would have sufiicient amplification to actuate a reasonably loud s e'aker,.while a No. 4 set might be so equippe as to fill a hall. For different classes of service as thus outlined, the subscriber should be charged different rates, as in long distance telephone service. ,It is very necessary that there be metering upon which to base the charges, since the service is atime service and not a message service. For this purpose I contemplate including in each cord a distinctive type of meter actuator which will operate the subscribers line meter, which may be his telephone meter or a separate meter as desired, a number of times per hour determined by the class of service he is receiving. Thus the No. 1 cord circuit may be I connected to a commutator that closes the line meter circuit once every hour; No. 2 may have ,a meter actuator that works twice every hour; No. 3 may have an actuator that works three times in the hour; while No. 4 may have its actuator work every tenor twelve minutes. The reason for selecting these time divisions is that the average charge per message for telephone service is about five cents. At five cents per hour, and averaging three hours service per day, a sub scribers radio bill would be $4.50 per month. This is fairly comparable to the earnings of an average residence telephone for the same period, on a message rate basis. The fractions of time could not be cut belowa five cent value, unless a separate-radio meter be provided for each line and it is desired to avoid this expense, as well as the upkeep of onehundred per cent of additional meters. In prior copending applications, Serial No. 581,831, filed August 14, 1922, and Serial No. 583,566, filed August 22, 1922, I have shown and described metering systems which are suitable for use with the system of circuits herein disclosed,;I have disclosed and shall inFig. together with the automatic actuat-f {it a claim the adaptation-of these metering circuits to the present system. i s It should be partieularly noted,'that-a sub-. scriber, (which term is meant to include any user) may not keep his radiophone in service a full hour, a pertinent example being that of a ,man who desires to obtain a baseball score orother special information." A special provision should be made for registering such service, as it involves all the elements of expense to the operating company which would be included in a much longer connec tion.l--For this purpose the operator may have a push button 9 connecting the actuating genera-tor G direct to the meter circuit through the plug 1?, as shownin one form ing means for the meter, comprising the commutator g which at stated intervals connects the generator G to the wire 297 leading to the third contact on the plug 1?, which when the plug is inserted in jack J completes the circuit from wire 297 through wire 298 to the cut oft relaywire 19 thence to the high winding 299 of the meter LM. In Fig. 3, the meter line meter, which would thus serve a double purpose, registering both the telephone calls and also the time of radiophone use in terms of telephone call units or telephone message units. Such a meter by reason of the high resistance in its winding 299 will not respond to the battery currentwhich energizes the cut off relay L but when the operatorconnects a generator as G producing current of higher voltage, then the meter magnet be-, comes sufliciently energized to attract its armature and close the circuit of its low winding 300, the rush of current through the. low winding producing strong and certain actuation of the metercounting device 301,

B thus having the operator always press the eys 9 immediately after making a radiophone'connection, there will always be made a base charge of one telephone message unit for the connection. If it should happen that the commutator closes theactuating circuit immediately afterward, the meter wouldre ister two units for the first hour of use. i f it should happenthat the subscriber hangs up in fifteen minutes the line would still bear the charge of two units for one hour.- On the other hand, if the connection was made immediately after the commutator had closed the metering circuit, then no addi-. tional charge would be made for an hour, and if the subscriber shouldhang up within less than an hour, he would have only the one charge against the line. In any event, the charge would ,be safe to the company and fair to the' subscriber asall public service corporations, make, a service chargeif the: measured rate charged is' below. a minimumamount.- A commutator individual to each? cord started when the cord is connected would of course'register individual 'time use only.

, Referring to Fig-5,- this isa schemati d gram showing without detail the layout of the subscribers line instruments and the central oflice radio connection just described and il-- lustrated in Figs. 3, 4,'and 4. Line wires shown at 18-19 extend-from the subscribers station A to the central office where they terminate on a jack J As the units of. the apparatus are marked with llegends specific. description is unnecessaryj The principal point is that no physical connection withzthe telephone line is made; at either ,endexcept through a tuned filter couplerpassing only superaudio frequencies. Y i? a; 9

Fig. 6. illustrates an'arrangement of apparatus and circuits for producing double mod-.

ulation of a primary or short carrier wave, that is to say, to modulate a relatively long. wave carrier, and then modulate this long wave upon a relatively short wave carrier which may conveniently be radiated in the usual fashion. -Means for receiving and de-.

modulating such double modulated waves have been described in connection with Figs.-

is shown a s the ordinary standard telephone j 3, 4 and In .Fig. 6, 150 is a microphone f coils 1'57, and is connected through radio jack coil 157", to the late of the-long wave oscillator tube-158'. he grid circuit of the tube connected to one coil coupler 161, whic in turn has a wire connection 160 back to the plate circuit. The coupler 161 is tuned on its input side to thelonggwave freqdency supplied by. the tube 158, and its secondary winding is connected to the grid circuit of a second modulator tube 162, containing a battery B", ;The plate circuit of the tube 162 is bridged by power battery 13 and choke coil 163, and is connected through the radio choke antenna circuit 57 is thus s11 :will be claimed herein? the same at both the B and C stations excoil 163 to the plate of the short wave oscillator tube 164. The grid circuit of this tube 164 contains ;a battery 13 and is connected through a condenser 167 and wire 167 to the antenna circuit, which is also 'connected back to the plate circuit through wire 166. The 'iied with short wave oscillations modulate y the'tube 162 with long wave oscillations which in turn have been modulated by the tube 154 with audio modulations due to the primary modulator or microphone transmitter 150. It shculd benoted that this circuit is an adaptation ofthe Heising modulator circuit in common use, audit is not claimed herein, being shown for example on page 682 of the work on Principles of radio communication by J. H. Morecroft, published byJohn Wiley & Sons, New York, 1921. The use. of. this apparatus however in combination with otherselements to produce the results stated," andthe adaptation or the circuit in question to the purposes ofthis system, are novel and- The apparatus of Fig. 7 is intended to receive a double modulated carrier wave such as thatradiated from the antenna in Fig. 6, demodulate the same and reimpo'se the long were or intermediate frequency, with its modulations, u 11 another short wave carrier which is it e carrier wave allotted to stations C or the subscribers stations VD, according as to whether the apparatus is situated at a B or C station, respectively. The purpose of this is to transmit from the point oforigin to the point of destination the same intermediate long wave carrier with the same audio modulations intact and merely passed along by relaying from station to station on short carrier waves.

The apparatus and circuits of Fig. 7 is cept that the transmitted or'short primary Referring as Fig. 7 in; etail, 5 1 is the receiving antenna coupled at 174 to the grid circuit of the detector 17 0,:whose plate 'circuit is connected through a tuned filter coupler 175 to the grid circuit of the amplifier tube 171,'wl1ose plate circuit is connected through the transformer 176 :to the grid circuit of the modulator tube 172, which in :158 contains a batterfy hi8, is diflerentiall turn has the usual Heising connections 178 179'tothe circuit of the oscillator tube 173; the radio choke coil 178, the power battery B and the magnetic choke coil 177 being arranged as usual. The grid and plate of' the oscillator tube 173 are connected to the antenna inductance coil 180, which withthe usual tuning condenser 180 is included inv the, antenna circuit 55. Filament batteries 13 ,3 and B fl 'and plate batteries B ancLB are located as usual. As thusdedescribed, the assemblageronstitutes a relay set which will take in: the modulated long waves on a short wave'scarrienand re= transmit them on a carrier or different frequency, without demodulating or disturbing the modulations of the intermediate or long wave,

Another arrangement of apparatus and circuits for performing functions similar to that-of the arrangement of Fig. 7, that is to relay on*a difi'erent carrier frequency carrying the same audio modulations, is shown in Figs. 8 and 9. Referring to Fig. 8, 1 85 is the receiving antenna'with coupler 186 connecting it to the detector'tube '181 which has a tripie coil oscillator coupler 187, 182 being the oscillator for producing local heterodynin waves. The detector circuit and the oscillator circuit are connected to the tuned filter coupler 188, the output side late circuit of B is the plate battery of the oscillator and the first tube 181, which, while I have called it a detector because it occupies that position, may be regarded rather as an amplifying tube, since it is worked by preference on the straight portion of the characteristic tube curve, for purposes 'which will appear. The battery B -'and battery "B are filament batteries for the tubes 183184 respectively, while B andv 22 are the platelbatteries for the same.- The antenna circuit radiates at a frequency determined by the tuning of the circuit 190, and it is to be observed that with this arrangement the radiated 'frequency is not the heat wave between the incoming wave from antenna 185 and the fre- 0 1 A 1.,1 l (,uvu

a frequency lower than any of said other carrier waves, and radiatin the same.

5. The method of .ra i0 rela ing which consists in receiving a. singly mo ulated carrier wave, transformin the same without demodulation into a dously modulated carrier wave in the form of a high frequency carrier 'wave modulated with'a carrier having a. frequency several times lower than that of said single modulated carrier wave and in turn modulated with the signal wave, amplifying I and radiatingsaid doubl modulated wave.

signature. Y o EDWARD E. CLEMENT.

In testimony .whereo I hereunto aflix my 7 is the mean frequency between these two, and also that the filter coupler 188 is tuned to this frequency. SeePrinciples of radio communication by J. H. Morecroft, page 636, ppblished by John Wiley 8: Sons, Inc., New ork, 1921. In these respects, the apparatus of Fig. 8 is very different from an ordinary superheterodyne set, which invariably makes use of the beat wave. In this case the heat wave is not taken off, but appears as an envelope on the mean frequency which is the carrier wave produced, amplified and radiated by the machine from the antenna 191. In other words, by heterodyning and then amplifying and radiating the wave carrying the original modulations, I produce what is really a double modulated carrier wave, since the mean frequency wave has an envelope corresponding exactly to the wave or beat fre uency between the original carrier and the eterodyning oscillator waves.

Referring to Fig. 9, the apparatus therein is a modification of what is shown in Fig. 8 but using autodyne receiving tube 182 instead of two tubes shown in Fig. 8. In this case the tube 182 is said to oscillate at the heterodyning frequency, while the circuit 186187 is tuned to the frequency of the incoming carrier wave. A resultant or mean frequency wave is produced, carrying the original modulations, and having an envelope of the frequency of the heat. This wave is propagated through the coupler 188 into the grid circuit of the tube 183, which is the first amplifier tube, and from thereon the operation is the same as described of Fi 8.

eferring now to Fig. 10, this is a further arrangement of apparatus and circuits for receiving on any short wave length and relaying by double modulation. The receiving antenna 200 is connected through coupler 201 to the grid circuit of the first detector 203, the input circuit being tuned by means of a variable condenser 202 as usual. The plate circuit of the detector 203 is connected to the tuned filter coupler 210, and the grid or input circuit is coupled through a triple coil coupler to the oscillator 204. The other side of the filter coupler 210 is connected to the grid circuit of the amplifying tube 205, the plate circuit of which goes to the transformer 211, the secondar of which is connected to the grid circuit 0 the amplifier tube 206, whose plate circuit is in turn connected to the transformer 212, the secondary of which feeds the grid circuit of the modulator tube 207, which is connected in a Heising transmission circuit including the oscillator tube 208, and the radiating circuit 215. The plate circuit of the oscillator tube 207 has the usual power battery B and choke coil 213, while the oscillating circuit of the tube 208 includes the resistance coil 214 and the tuning elements of the antenna circuit. Battery 13 is the plate batlator tube 204. B is the filament battery of the amplifier tubes, B is the high voltage plate battery of the same, B is the power attery of the modulator oscillator circuit while battery B is a grid battery for the oscillator tube 208. B is the filament battery for the same tube.

This arrangement of Fig. 10 is the same as the ordinary supheterodyne circuit up to the tube 207. According to usual practice this tube would be a second detector and would be followed by one or more stages of audio amplification. In the present case, this tube is a modulator, which takes the heat waves passed through the tuned filter coupler 210, and amplified in the tubes 205--206, and imposes them on the high frequency carrier current generated by the tube 208 and radiated from the antenna 215. This shows another method of taking a single modulated incoming wave and by heterodyning and remodulating, sending out the same audio modulations unchanged on a different carrier wave. The waves radiated from the antenna 215 also require receiving instruments capable of double demodulation.

What I claim is:

1. A radio relay apparatus for relaying singly modulated carrier waves comprising means to receive a modulated carrier wave, means to combine therewith a second wave within the range of beating frequencies to produce a composite double modulated carrier wave of a third frequency bearing the beat frequency modulated with the original signal modulations, and means for amplifying and radiating said third frequency wave.

2. The radio relay apparatus described in claim 1 with a filter coupler following the combining means and tuned'to the third frequency.

3. The method of radio relaying which comprises the following steps: receiving a singly modulated carrier wave, then combining a second wave of beating frequency with the same to produce a third or intermediate or mean frequency wave bearing an envelope corresponding to the beat, also bearing thereon the original low frequency signal modulation, then amplifying said intermediate wave with its envelope and modulation and radiating the same at said third or intermediate frequency.

4. The method of relaying radio signals which consists in receiving a singly modulated carrier wave, combining therewith a second Wave to produce thereby a doubly modulated carrier consisting of a third frequency intermediate that of said first and second waves and modulated with a carrier having 

